Some buildings, such as houses or offices, are usually disposed with central air conditioning systems. The central air conditioning system includes a central main machine and a plurality of vents (or called as outlets or inlets) for distribution of hot or cold air. The vents are installed in many different rooms. The vents are connected with the central main machine through vent pipes (or called as ducts). The central main machine generates hot air flows or cold air flows. The hot air flows or the cold air flows are delivered to many different rooms through the vent pipes. Therefore, the central air conditioning system may enable air to ventilate in the building and regulate the temperature inside the building and individual rooms in the building.
A damper is usually disposed in each vent to adjust a ventilation amount. However, the damper needs manual operation. A user operating the damper is unable to operate every damper frequently. When the user leaves a room but does not turn off the damper, the hot air flows or the cold air flows generated by the central main machine will be delivered to some rooms without people in, thus causing energy wastage.
In addition, as the dampers are all adjusted in a manual manner, the central main machine is not capable of controlling the required amount of cold/hot air flow by taking into account the current damper settings. Therefore, the central main machine will cause either insufficient or excessive air flow leading to inefficiency. There is a growing need to improve the efficiency of HVAC (heating, ventilating, and air conditioning) systems to combat carbon emissions and a trend towards smart buildings. The central air conditioning system also has to have some automatic control functions. The central air conditioning system having automatic control functions may adjust the ventilation of the hot air flow or the cold air flow automatically, thereby achieving an energy-saving effect. Patents having proposed related conceptions includes U.S. Pat. No. 5,271,558 U.S. Pat. No. 5,348,078, U.S. Pat. No. 5,927,599, and U.S. Pat. No. 5,761,083.